Conventional copper electrowinning processes produce copper cathode sheets. Copper powder, however, is an alternative to solid copper cathode sheets. Production of copper powder as compared to copper cathode sheets can be advantageous in a number of ways. For example, it is potentially easier to remove and handle copper powder from an electrowinning cell, as opposed to handling relatively heavy and bulky copper cathode sheets. In traditional electrowinning operations yielding copper cathode sheets, harvesting typically occurs every five to eight days, depending upon the operating parameters of the electrowinning apparatus. Copper powder production has the potential, however, of being a continuous or semi-continuous process, so harvesting may be performed on a substantially continuous basis, therefore reducing the amount of “work-in-process” inventory as compared to conventional copper cathode production facilities. Also, there is potential for operating copper electrowinning processes at higher current densities when producing copper powder than with conventional electrowinning processes that produce copper cathode sheets, capital costs for the electrowinning cell equipment may be less on a per unit of production basis, and it also may be possible to lower operating costs with such processes. It is also possible to electrowin copper effectively from solutions containing lower concentrations of copper than using conventional electrowinning at acceptable efficiencies. Moreover, copper powder exhibits superior melting characteristics over copper cathode sheets and copper powder may be used in a wider variety of products than can conventional copper cathode sheets. For example, it may be possible to directly form rods, shapes, and other copper and copper alloy products from copper powder.
Conventional cathodes used in conventional electrowinning cells do not allow electrolyte to flow through the cathode, and the mass transport at the surface of the cathode depends on the efficiency of electrolyte mixing between and among the cathodes in the electrowinning cell. The present inventors have recognized that a flow-through cathode design that would allow a significant increase in mass transport of relevant species to and from the cathode and the anode by improving the overall flow characteristics through an electrowinning cell would be advantageous, particularly for a copper powder production process. In particular, when one or more flow-through cathodes are utilized in combination with one or more flow-through anodes within the electrowinning cell, significant enhancements to mass transport of ionic species to and from the surfaces of the anodes and cathodes can be achieved.